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Full text of "Practical Organic Chemistry"

APPENDIX

33i

and pipenclitie are neutral ; salts of aromatic bases (ammo-
group in tlie nucleus) are acid. A soluble organic base (lower
amine, ben zylamine, pyridine) will be detected by its smell. Most
aromatic a. nil no-compounds and alkaloids are insoluble in water.
Some aromatic diamines and aminophenols are moderately
soluble. '-The nature of the amine, whether primary, secondary,
or tertiary, should then be investigated as described under  II.

of both the aliphatic and aromatic series will also
come under tliis head. Substances like glycocoll, alanine, etc., are
very soluble in water, giving neutral solutions, and may be
identified toy means of the copper salt (see p. 91). Ammo-acids
of the aliphatic series also evolve nitrogen when treated with
sodium nitrite and hydrochloric acid, and give off amines when
heated with soda-lime. Ammo-acids of the aromatic series
may be cliazotised and coupled with phenols, like aromatic
amines (see p. 151).
Amides and Cyanides.  Many amides and a few cyanides are
soluble iii water. They are decomposed by hot concentrated
aqueous or alcoholic caustic soda solutions, by concentrated
hydrochloric acid or sulphuric acid (equal vols. of acid and water)
on long reflux boiling. In the first case, ammonia is evolved ; in
the latter two case's, salts of ammonia are formed, which yield
ammonia on heating with excess of caustic soda. Anilides
behave si milarly, but aniline in place of ammonia is liberated and
must be looked for. Some amides are difficult tohydrolyse with
any of tliese reagents. In such cases, gently heating with
a mixture of one volume of cone, sulphuric acid and two
volumes of ethyl alcohol will yield the ester of the acid and
ammonium sulphate. The ester can then be separated by
adding n. little water and extracting with ether, and can be hydro-
lysecl arid the organic acid identified (see p. 333), whilst the
aqueous solution, after driving off dissolved ether, will give the
smell of smimonia on warming with excess of alkali.
3. Contains Halogen.  It may be a halogen add (e.g.,
chloracetic acid) or its salt, or the hydrochloride of a base or
timino-tif~/rfi or a substituted aldehyde (chloral, butyl chloral).
If it is ct free halogen acid, the solution will have an acid reaction,
and the solution will remain clear on adding caustic soda. If it
is? the hydrochloride of a base, it will give a precipitate with